1) Alarm 2) Appal 3) Cow 4) Daunt 5) Dismay 6) Faze 7) Rattle 8) Unman 9) Unsettle 10) Worry 1) Alarm 2) Baffle 3) Befuddle 4) Bewilder 5) Cause to lose courage 6) Daunt 7) Deprive of courage 8) Discombobulate 9) Discomfit 10) Discompose 11) Disconcert 12) Disturb the composure of 13) Enervate 14) Faze 15) Flummox 16) Frighten 17) Intimidate 18) Mystify 19) Psych out 20) Puzzle 21) Rattle 22) Set on edge 
• (v. t.) To deprive of nerve, force, or strength; to weaken; to enfeeble; as, to unnerve the arm.
to deprive of courage, strength, determination, or confidence; upset: Fear unnerved him.
disturb the composure of